Sigma Phi Lambda is another Christian national sorority, and they have a lot of chapters around Texas that I know of. Here's their wiki:
http://en.wikipedia.org/wiki/Sigma_Phi_Lambda
(I couldn't get the
www.sigma-phi-lambda.com site to work for some reason.)
Other smaller sororities that I can name off the top of my head would be multicultural ones like Kappa Delta Chi, alpha Kappa Delta Phi, and Theta Nu Xi. I'm not sure if they pertain to this list or if they're in another council or not, but there they are.